Side seals to be attached to the slider of a linear guide have a structure such that a seal main body formed of an elastic material such as elastomer is sandwiched between a holder and a cover as disclosed in, for example, the following Patent Document 1. According to such a structure, the soft seal main body is held between the hard holder and cover so that an assembly can be made. This facilitates handling of such an assembly at the time of assembling and improves the assembling precision.